Fuel cells are designed to facilitate electrochemical reactions for generating electrical power. One required function in fuel cells is directing reactants in a desired manner through the fuel cell. Flow field plates typically include channels through which fluids flow during fuel cell operation. For example, a fuel gas or air is directed along flow field channels such that the gas is available at a catalyst layer of a polymer electrolyte membrane fuel cell.
Flow field channels typically have been provided on flow field plates arranged in parallel fashion. Typical flow field channel arrangements have a plurality of inlets on one side of the plate and corresponding outlets on the other side. In conventional arrangements, ribs on the flow field plate separate the individual channels.
It has also been suggested to use interdigitated flow field arrangements. These differ from conventional flow field arrangements by having a fluid enter the inlet of one channel, but exit the outlet of another channel. FIG. 1 schematically illustrates an example flow field plate arrangement 20 according to the prior art. In this example, a plurality of inlet channels 22 are arranged in parallel with a plurality of outlet channels 24. As schematically illustrated by the arrows 26, a selected fluid such as a fuel gas or air flows into the inlet channels 22 across a region including ribs 28 between the channels. The fluid flow from the inlet channels 22 to the outlet channels 24 includes approximately one-half of the flow within each inlet channel 22 transferring over to a corresponding outlet channel 24. In other words, the fluid flowing in each inlet channel is effectively diverted into two separate outlet channels 24 with approximately one-half of the flow from each inlet channel going into a corresponding outlet channel.
Example interdigitated flow field channels are described in U.S. Pat. Nos. 6,416,892; 6,472,095; 6,485,857; 6,780,533; and 6,794,077. While such arrangements provide performance enhancements, those skilled in the art are always striving to make further improvements.